As shown in FIG. 9, a conventional wrench 90 comprises a handle 91, a toothed portion 92, a curved jaw 93, a connecting rod 94 and a change-over switch 95. The handle 91 comprises a trough 911. The trough 911 forms a first slot 911A and a second slot 911B therein. The toothed portion 92 is formed at an end of the handle 91. The curved jaw 93 is pivotally connected to the handle 91. One end of the connecting rod 94 is pivotally connected to the curved jaw 93 while the other end of the connecting rod 94 is pivotally connected to the change-over switch 95. The change-over switch 95 comprises a positioning pin 951. In this manner, when the change-over switch 95 is pushed and the positioning pin 951 is correspondingly located in either the first slot 911A or a second slot 911B, the connecting rod 94 is moved simultaneously to pull the curved jaw 93 pivoting so as to adjust a size of an opening between the curved jaw 93 and the toothed portion 92 for fitting with nuts of different sizes.
However, based on such adjusting design, there are only two adjustable sizes of the opening between the curved jaw 93 and the toothed portion 92 (the positioning pin 951 is correspondingly located in either the first slot 911A or a second slot 911B), and only at most three nut sizes can be applied for the conventional wrench. Therefore, the conventional wrench has a drawback of low applicability.
Accordingly, it is necessary to invent improved new products to overcome the above-mentioned shortcomings and problems.